Lathrobium sapaensis Tokareva & Bekchiev, 2025

Tokareva, Alexandra, Bekchiev, Rostislav & Nguyen, Hieu Van, 2025, Description of a new species of Lathrobium Gravenhorst, 1802 (Staphylinidae: Paederinae) from Vietnam based on integrative taxonomy, Zootaxa 5725 (2), pp. 292-300 : 294-298

publication ID	https://doi.org/10.11646/zootaxa.5725.2.7
publication LSID	lsid:zoobank.org:pub:8EE65275-AF14-4408-B554-60FAF7D1FE72
persistent identifier	https://treatment.plazi.org/id/DB7E9766-FFE2-1017-FF01-FADBFD01FCDD
treatment provided by	Plazi
scientific name	Lathrobium sapaensis Tokareva & Bekchiev
status	sp. nov.

Treatment

Lathrobium sapaensis Tokareva & Bekchiev sp. nov.

urn:lsid:zoobank.org:act:

( Figs 1–2 View FIGURE 1 View FIGURE 2 )

Type material. Holotype ♀: “ VIETNAM: Fansipan Mts; Hoang Lien National Park, near Sa Pa waterfall; Lao Cai Province; h = 1815 m, 22.36198N, 103.77795E, 24.X.2023, leg. Bekchiev R., Simov N., Langourov M./ DNA voucher 2024 NMNHS-LAT-001/ Holotypus ♀ Lathrobium sapaensis sp. nov., det. A. Tokareva 2025 ” ( NMNHS). GoogleMaps

Etymology. The specific epithet is an adjectival form derived from Sa Pa, the forest waterfall in mountainous Lao Cai Province, Vietnam, where nearby the species was discovered.

Diagnosis. Head round-triangular; epicranium with punctures slightly less dense in median dorsal portion; eyes small; antennae shorter than head and pronotum combined. Pronotum very elongate, nearly parallel-sided, slightly narrowed behind posterior angles. Elytra short, widening posteriorly; hind wings vestigial. Tergite VIII posteriorly produced at nearly right angle; sternite VIII conical, sides slightly concave, apex blunt. Paraprocts (tergite IX) anteriorly separated by membrane; proctiger (tergite X) elongate, conical. Coxites and valvifers of sternite IX separate.

Description. Body length 7.2 mm; length of forebody 3.4 mm. Habitus as in Fig. 1 View FIGURE 1 . Coloration: head, antennal bases, and tibial bases dark brown, rest of body brown to light brown.

Head ( Fig. 1A View FIGURE 1 ) as long as wide, round-triangular, widest at posterior. Epicranium with moderately coarse and sparse punctation with punctures slightly less dense in median dorsal portion ( Fig. 1A, B View FIGURE 1 ); punctures more than one diameter apart; dorsal integument with clear microreticulation ( Fig. 1E View FIGURE 1 ); surface of head shiny; neck ½ as wide as head. Eyes small, composed of 40 ommatidia ( Fig. 1C View FIGURE 1 ), approximately one-sixth as long as postocular side of head in dorsal view. Ventral side of head with integument with clear microreticulation ( Fig. 1F View FIGURE 1 ); gular sutures slightly concaved towards each other but completely separate, converging towards neck ( Fig. 1D View FIGURE 1 ). Head setation prominent, setae distribution as in Fig. 1A–D View FIGURE 1 . Antennae 2.6 mm long, moniliform, shorter than head combined with pronotum, scapus slightly longer than antennomeres II and III combined, antennomeres II and II elongate, antennomeres IV–X obconic, longer than wide but become progressively wider; antennomere XI elongate, subacute.

Pronotum ( Fig. 1A, D View FIGURE 1 ) significantly longer than wide, narrower than head and elytra, slightly narrowed after posterior angles, posterior edge as wide as anterior edge; punctation sparse, less coarse than that of epicranium; punctures more than one diameter apart; midline impunctate; integument with no to very shallow interrupted microsculpture; surface of pronotum shiny.

Mesoventral plate ( Fig. 1D View FIGURE 1 ) typical for type 12 for Lathrobiina (see details in Tokareva & Żyła, 2025, figs. 4F, 10G), nearly as long as wide; anepisternal ridges (taar) reaching anterior margin of mesoventrite; posterior anepisternal ridge (par) has additional short acute angle on each lateral side curved posteriad on ventrite; prepectal window wide, rectangular, shield-shaped, shorter than posterior portion of ventrite; posterior median portion of ventrite nearly as long as wide, flat, with prominent secondary ridge (vvmr) protruding vertically from posterior acute process of ventrite reaching acute angle formed by prepectal window.

Elytra ( Fig. 1A View FIGURE 1 ) approximately 1.6 of length of pronotum, widening posteriorly; punctation fine, sparse, shallow; setation sparce, with medium-length setae; integument without microsculpture, surface shiny; posterior edge without fringe of microsetae. Hind wings vestigial.

Abdomen ( Fig. 1A View FIGURE 1 ) broader than elytra; punctation dense and fine; setation sparce, with short and medium-length setae on tergite and sternite plates and long macrosetae close to edges of each plate and on paratergites; integument with fine microsculpture.

♀: Tergite VII with posterior edge straight, sternite VII with posterior edge straight, without modifications or fringes of wide microsetae; tergite VIII with posterior edge produced in straight angle in middle ( Fig. 2A View FIGURE 2 ), sternite VIII conical, with posterior edges slightly concaved towards each other and blunt apex with slightly ragged edge bearing light short micropubescence ( Fig. 2B View FIGURE 2 ), but without any fringe of wide microsetae; paraprocts separated by membrane anteriorly, apices acute, slightly curved upwards ( Fig. 2C View FIGURE 2 ), longer than basal portion; proctiger conical; sternite IX with coxites and valvifers separate and free ( Fig. 2D View FIGURE 2 ); subgenital plate largely membranous, elongate, slightly rectangular ( Fig. 2E View FIGURE 2 ).

♂: Unknown.

Comparative notes. Lathrobium sapaensis Tokareva & Bekchiev sp. nov. is distinguished from the other species known from this area ( Vietnam, Southern China ( Yunnan)) by the following combination of characters: head round-triangular, epicranium with punctures slightly less dense in median dorsal portion; pronotum very elongate, slightly narrowed after posterior angles, of even width throughout; elytra short, widening posteriorly; shape and proportions of female terminalia.

Compared to the only other species known from Vietnam, L. austere , the new species is slightly larger, lighter in coloration, with narrowing area after posterior angles of pronotum, anteriorly separated paraprocts (tergite IX), and conical, longer proctiger (tergite X).

In comparison with L. coadultum , the new species has another shape of pronotum (more rectangular, of even width throughout), less tapering median process of tergite VIII, different shape of sternite VIII, nothing comparable to the segments IX and X modification as in L. coadultum .

Compared to L. daweianum , the new species is much larger, its head is wider than pronotum, it has different shape of tergite and sternite VIII and anteriorly separated paraprocts (tergite IX).

In comparison with L. bifasciatum , the new species is larger, has bigger eyes, different shape of pronotum and structure of female terminalia.

Along with that, Lathrobium sapaensis Tokareva & Bekchiev sp. nov. COI barcode fragment sequence differs from that of L. austere , L. coadultum , and L. bifasciatum in numerous positions (see the sequences alignment as the Supplement 1).

Distribution and natural history. Lathrobium sapaensis Tokareva & Bekchiev sp. nov. is the second species of the genus to be described from Vietnam. The type locality is situated near a forest waterfall, in the mountains of the Northern part of Vietnam, ~ 100 km from the border with Southern China ( Yunnan). This locality is almost at the same latitude as the type locality of L. austere , but the latter formally remains the southernmost species of Lathrobium described.

Barcodes distance matrix

According to the distance matrix, presented in the Table 2, the compared COI fragment of the barcoding region for Lathrobium sapaensis Tokareva & Bekchiev sp. nov. has unique sequence that drastically differs from all species brought to comparison. The estimated evolutionary divergence between Lathrobium sapaensis Tokareva & Bekchiev sp. nov. and the only other species known from Vietnam, L. austere , turned out to be slightly larger (0.17 base substitutions per site between sequences) than between the new species and L. coadultum from China (0.16 base substitutions per site between sequences).

At the same time, the estimated evolutionary divergence between the new species and L. bifasciatum , another similarly looking species from China, is nearly as large (0.20 base substitutions per site between sequences) as between the new species and the single representative of another genus, Tetartopeus (0.22 base substitutions per site between sequences).

number of base substitutions per site between sequences.